The options to open or close purchase Order or request must be readily available. Most at times, users mistakenly click on close order thinking it means to finalize the order and ends up cancelling the process instead. when this happens, you can only contact the software developers and wait for days to get it resolved which is very frustrating
Video:
https://www.youtube.com/watch?v=gY2musD-11g
Article:
https://www.greytrix.com/blogs/sagex3/2013/05/17/reopen-closed-purchase-orders/